1. Field of the Invention
The present invention generally relates to an electronic camera, and more particularly to an electronic camera that warns of an obstruction to an automatic electronic flash, a method for detecting the obstruction and a method for correcting an exposure level.
2. Description of Related Art
An electronic camera has been reduced in size in recent years, and a finger of the user is apt to obstruct a built-in electronic flash when the user points the camera at a subject.
To address this problem, Japanese Patent Provisional Publication No. 7-306453 discloses a camera that has an obstruction sensor measuring the capacitance of a capacitor arranged beside the electronic flash and warns the user of the obstruction in accordance with the change of the capacitance. Also, Japanese Patent Provisional Publication No. 10-221761 discloses a camera, in which the more important members are, the farther the members are arranged from the fingers of the user, to minimize the bad effect when the finger obstructs the members.
When the finger obstructs a window of an automatic electronic flash, the finger reflects the flash and the reflected light enters an electronic flash adjusting sensor. Accordingly, the electronic flash quickly adjusts the flash, and an imaging device is under-exposed as a result.
When the camera has the obstruction sensor, however, a space for the obstruction sensor is required and thus the camera becomes larger and its cost is increased. On the other hand, if only the electronic flash adjusting sensor is arranged far from the electronic flash window, the camera can not warn the user of the obstruction, moreover, circuits are not appropriately constructed for reducing the size of the camera since the electronic flash adjusting sensor is far from an electronic flash circuit and wires are long.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of an electronic camera that can detect an obstruction to an electronic flash and warn of the obstruction without a special obstruction sensor, and a method for detecting the obstruction.
The present invention has as another object the provision of an electronic camera that can warn that a flash does not reach a subject or correct the exposure level when the flash does not reach the subject, and an exposure level correcting method.
To achieve the above-described object, the present invention is directed to an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the electronic camera comprising: an electronic flash; a first determining device which determines whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting; a second determining device which determines whether an output of the electronic flash is at a maximum thereof; a judging device which judges, when the first determining device determines that the imaging device is under-exposed at the electronic flash shooting and the second determining device determines that the output of the electronic flash is not at its maximum, that the electronic flash is obstructed; and a warning device which warns that the electronic flash is obstructed when the judging device judges that the electronic flash is obstructed.
According to the present invention, it is judged that the electronic flash is obstructed when the under-exposure is detected and it is determined that the output of the electronic flash is not at its maximum (the emission is stopped before reaching its maximum) in accordance with the image data captured at the electronic flash shooting. When the electronic flash is obstructed by an obstruction (e.g., a finger of the user), the obstruction reflects the flash and the reflected light enters an electronic flash adjusting sensor. Accordingly, the electronic flash is quickly stopped, and the output of the electronic flash is thereby small and the imaging device is underexposed as a result. In this case, there is a warning that the electronic flash is obstructed.
Preferably, the second determining device determines whether the output of the electronic flash is at the maximum thereof in accordance with at least one of an emission time of the electronic flash and a change in voltage of a capacitor powering the electronic flash between before and after the electronic flash shooting.
To achieve the above-described object, the present invention is directed to an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the electronic camera comprising: an electronic flash; a first determining device which determines whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting; a second determining device which determines whether an output of the electronic flash is at a maximum thereof; a judging device which judges, when the first determining device determines that the imaging device is under-exposed at the electronic flash shooting and the second determining device determines that the output of the electronic flash is at its maximum, that a flash of the electronic flash does not reach the subject; and a correction device which corrects, when the judging device judges that the flash does not reach the subject, an exposure level of the image data captured at the electronic flash shooting and then records the image data in the recording medium.
According to the present invention, it is judged that the flash does not reach the subject when the under-exposure is detected and it is determined that the output of the electronic flash is at its maximum in accordance with the image data acquired at the electronic flash shooting. When it is judged that the flash does not reach the subject, the exposure level of the image data captured at the electronic flash shooting is corrected (raised in gain) and then the corrected image data is recorded in the recording medium. The warning device may warn that the flash does not reach the subject.
To achieve the above-described object, the present invention is directed to an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the electronic camera comprising: an electronic flash; a first determining device which determines whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting; a second determining device which determines whether an output of the electronic flash is at a maximum thereof; a first judging device which judges, when the first determining device determines that the imaging device is under-exposed at the electronic flash shooting and the second determining device determines that the output of the electronic flash is not at its maximum, that the electronic flash is obstructed; a second judging device which judges, when the first determining device determines that the imaging device is under-exposed at the electronic flash shooting and the second determining device determines that the output of the electronic flash is at its maximum, that a flash of the electronic flash does not reach the subject; and a warning device which warns that the electronic flash is obstructed when the first judging device judges that the electronic flash is obstructed and which warns that the flash does not reach the subject when the second judging device judges that the flash does not reach the subject.
To achieve the above-described object, the present invention is directed to an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the electronic camera comprising: an electronic flash; a first determining device which determines whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting; a second determining device which determines whether an output of the electronic flash is at a maximum thereof; a first judging device which judges, when the first determining device determines that the imaging device is under-exposed at the electronic flash shooting and the second determining device determines that the output of the electronic flash is not at its maximum, that the electronic flash is obstructed; a second judging device which judges, when the first determining device determines that the imaging device is under-exposed at the electronic flash shooting and the second determining device determines that the output of the electronic flash is at its maximum, that a flash of the electronic flash does not reach the subject; a warning device which warns that the electronic flash is obstructed when the first judging device judges that the electronic flash is obstructed; and a correction device which corrects, when the second judging device judges that the flash does not reach the subject, an exposure level of the image data captured at the electronic flash shooting and then records the image data in the recording medium.
To achieve the above-described object, the present invention is directed to an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the electronic camera comprising: an electronic flash; a first determining device which determines whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting; a rangefinder which measures a subject distance; a second determining device which determines whether the subject distance measured by the rangefinder at the electronic flash shooting is at most a predetermined reach of flash; a judging device which judges, when the first determining device determines that the imaging device is under-exposed at the electronic flash shooting and the second determining device determines that the subject distance is at most the predetermined reach of flash, that the electronic flash is obstructed; and a warning device which warns that the electronic flash is obstructed when the judging device judges that the electronic flash is obstructed.
To achieve the above-described object, the present invention is directed to a method for detecting an obstruction to an electronic flash of an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the method comprising the steps of: determining whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting and determining whether an output of the electronic flash is at a maximum thereof; and judging that the electronic flash is obstructed when it is determined that the imaging device is under-exposed at the electronic flash shooting and it is determined that the output of the electronic flash is not at the maximum thereof in the determining step.
Preferably, the determining step comprises, to determine whether the output of the electronic flash is at the maximum thereof, at least one of the steps of: determining an emission time of the electronic flash; and determining a change in voltage of a capacitor powering the electronic flash between before and after the electronic flash shooting.
To achieve the above-described object, the present invention is directed to an exposure level correcting method in an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the exposure level correcting method comprising the steps of: determining whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting and determining whether an output of the electronic flash is at a maximum thereof; and judging that a flash of the electronic flash does not reach and correcting an exposure level of the image data captured at the electronic flash shooting when it is determined that the imaging device is under-exposed at the electronic flash shooting and it is determined that the output of the electronic flash is at the maximum thereof in the determining step.
To achieve the above-described object, the present invention is directed to a method for detecting an obstruction to an electronic flash of an electronic camera which records image data of a subject captured through a taking lens and an imaging device into a recording medium, the method comprising the steps of: determining whether the imaging device is under-exposed in accordance with the image data captured at an electronic flash shooting, measuring a subject distance, and determining whether the subject distance is at most a predetermined reach of flash; and judging that the electronic flash is obstructed when it is determined that the imaging device is under-exposed at the electronic flash shooting and it is determined that the subject distance is at most the predetermined reach of flash.